Hitherto, a conveying device is known which conveys a rack on which a sample container is held to a sample supplying position for supplying a sample to a sampler processing device for processing the sample (refer to, for example, Japanese Patent Laid-Open (JP-A) No. Hei 9-43246). The sample processed by the processing device is contained in a sample container held on the rack. JP-A No. H9-43246 discloses a conveying device having a buffer, a first feeder, and a second feeder.
In the conveying device disclosed in JP-A No. H9-43246, the buffer has the functions of storing a rack introduced from an introduction port of the conveying device and conveying the stored rack to the first feeder. The first feeder has the function of conveying the rack conveyed from the buffer to a sample supplying position and the second feeder. The second feeder has the function of carrying out the rack conveyed by the first feeder to the outside from an outlet of the conveying device. The buffer, the first feeder, and the second feeder can convey the racks only in one direction. Concretely, the racks conveyed from the buffer are moved only toward the first feeder side. The racks conveyed from the first feeder are moved only in a direction toward the sample supplying position (second feeder). The racks conveyed by the second feeder are moved only in a direction toward the outlet of the conveying device.
When an error occurs in the sample processing device during process of a predetermined sample in the conventional conveying device, in order to re-process the predetermined sample in the same sample processing device, a predetermined rack on which a sample container containing the predetermined sample is held is re-stored in the buffer, and the predetermined rack has to be conveyed again to the sample supplying position by the first feeder. In this case, since the conveying device of JP-A No. H9-43246 is constructed so that the racks are conveyed only in one direction in the buffer, there is an inconvenience such that the user has to move racks already stored in order to assure a space for re-storing the predetermined rack. The technique of JP-A No. H9-43246 has a drawback that the burden on the user is heavy at the time of re-processing a sample in the same sample processing device.